| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D940804.1 | Possible error in humidity ground check | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| D941104.1 | Bad surface RH value in sounding | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| D941108.2 | Bad surface RH value in sounding | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| D941108.4 | CF Sonde Ground Check Corrections | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| D941213.1 | Questionable initial values sounding 941209:1133 | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/13/1994 | 1131 | 08/03/1994 | 1430 |
| Subject: | Possible error in humidity ground check |
| DataStreams: | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| Description: | DQR No: Platform: sgpsondewrpnC1
Subject: Possible error in humidity ground check
Date Submitted: 8/3/94
Submitted By: Barry Lesht _X_ Instrument Mentor
___ EST Member
___ Science Team Member
___ Other _____________________________
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at dqr@arm.gov.
Platform/Measurement:
What level data: (raw,a0,a1,b1,c1 etc): raw, a0, a1
What location was the data collected at: CF
Period of time in question
Begin Date 7/13/94 Time 11:31 (GMT)
End Date 8/ 3/94 Time 14:30 (GMT)
Data should be labeled:
_X_ questionable ___ All data fields affected
___ incorrect _X_ Only some data fields affected
___ wrong calibration
___ others
Discussion of Problem:
We suspect that the dessicant in the bbss ground check set (located
only at the central facility) has become saturated and is no longer
providing a 0 %RH environment against which to check the sonde RH sensor.
This would result in a bias in the correction for humidity for
those soundings that were done during the time the dessicant was bad.
Examination of the data suggests that the potential errors are small,
(on the order of a few percent RH), but sufficiently different from previous
corrections to warrant temporary suspension of the ground check procedure.
A review of the data collected since the beginning of the year shows no
trend in humidity correction until July 13, 1994. The last positive
humidity correction was recorded on July 12, 1994 and since then has been
noticably (though slightly) downward.
The humidity correction is applied linearly. That is, U = U' + (Uo - Uo')
where U is the humidity with the ground check applied (this is the RH
value in our data stream), U' is the humidity measured at the sonde before
correction, Uo is the reference humidity (assumed to be 0%), and Uo' is
is the humidity measured by the sonde in the ground check set. Users
can recover the RH measured at the sonde by subtracing the global attribute
"humidity-correction" from the RH values in the data set. Based on our
experience with the ground check data, we expect the RH values measured
at the sonde to be accurate within +/-2% RH.
Other observations/measurements impacted by this problem:
Any measurement derived from the sonde RH measurement, for example
dew point temperature, water vapor mixing ratio).
Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)
Flag data warning user that RH may be biased high by an unknown amount,
probably not exceeding 2% RH.
Data Processing Notes Date |
| Measurements: | sgpsondewrpnC1.a1:
sgpsondewrpnC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 10/30/1994 | 2326 | 10/30/1994 | 2326 |
| Subject: | Bad surface RH value in sounding |
| DataStreams: | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| Description: | DQR No: Platform: SGPSONDEC1
Subject: Bad surface RH value in sounding 10/30/94 23:26
Date Submitted: 11/4/94
Submitted By: Barry Lesht _X_ Instrument Mentor
___ EST Member
___ Science Team Member
___ Other _____________________________
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at dqr@arm.gov.
Platform/Measurement: All
What level data: (raw,a0,a1,b1,c1 etc):
What location was the data collected at: SGP/CF
Period of time in question
Begin Date 10/30/94 Time 23:26 (GMT)
End Date 10/30/94 Time 23:26 (GMT)
Data should be labeled:
___ questionable ___ All data fields affected
_X_ incorrect _X_ Only some data fields affected
___ wrong calibration
___ others
Discussion of Problem:
It looks as though an incorrect value was entered by the operator for
surface relative humidity. The value entered 16% is much lower than the
first value given by the radiosonde 80%. The rest of the sounding is
consistent with humid, rainy conditions, suggesting a typographical
error (16 instead of 76?).
Other observations/measurements impacted by this problem:
Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)
Flag data.
Data Processing Notes Date |
| Measurements: | sgpsondewrpnC1.a1:
sgpsondewrpnC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/06/1994 | 1733 | 11/06/1994 | 1733 |
| Subject: | Bad surface RH value in sounding |
| DataStreams: | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| Description: | DQR No: Platform: SGPSONDEC1
Subject: Bad surface RH value in sounding 11/6/94 17:33
Date Submitted: 11/8/94
Submitted By: Barry Lesht _X_ Instrument Mentor
___ EST Member
___ Science Team Member
___ Other _____________________________
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at dqr@arm.gov.
Platform/Measurement: All
What level data: (raw,a0,a1,b1,c1 etc):
What location was the data collected at: SGP/CF
Period of time in question
Begin Date 11/06/94 Time 17:33 (GMT)
End Date 11/06/94 Time 17:33 (GMT)
Data should be labeled:
___ questionable ___ All data fields affected
_X_ incorrect _X_ Only some data fields affected
___ wrong calibration
___ others
Discussion of Problem:
An incorrect value was entered by the operator for surface relative humidity.
The value as entered as 4% should be 45%. This typographical error was
noted in the site operations log by the operator shortly after it occurred.
The remaining values in the sounding should be fine.
Other observations/measurements impacted by this problem:
Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)
Flag data.
Data Processing Notes Date |
| Measurements: | sgpsondewrpnC1.a1:
sgpsondewrpnC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/21/1993 | 1640 | 08/03/1994 | 1430 |
| Subject: | CF Sonde Ground Check Corrections |
| DataStreams: | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| Description: | DQR No: Platform: SGPSONDEC1
Subject: CF Sonde Ground Check Corrections
Date Submitted: 11/8/94
Submitted By: Barry Lesht _X_ Instrument Mentor
___ EST Member
___ Science Team Member
___ Other _____________________________
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at dqr@arm.gov.
Platform/Measurement: sgpsondec1
What level data: (raw,a0,a1,b1,c1 etc): all
What location was the data collected at: SGP/CF
Period of time in question
Begin Date 01/21/93 Time 16:40 (GMT)
End Date 08/03/94 Time 14:30 (GMT)
Data should be labeled:
_?_ questionable ___ All data fields affected
___ incorrect _X_ Only some data fields affected
___ wrong calibration
___ others
Discussion of Problem:
Between 1/21/93 and 8/3/94 all radiosondes launched from the central
facility were ground checked before launch. The ground check procedure
consists of placing the sonde sensor arm into a sealed, dessicated chamber
containing a certified calibrated mercury thermometer, allowing the sonde
to equilibrate, and comparing the sonde output readings for RH and
temperature to the thermometer reading and an assumed 0% RH. All data after
launch were "corrected" to account for any differences between the sonde
output and the reference conditions in the ground check set.
Analysis of the population of ground check values shows that the average
RH correction was 0% RH and average temperature correction was -0.4 degC.
Because there is some question as to whether applying the ground check
correction increases or decreases the accuracy of the output data, some
investigators may wish to remove the effect of the ground check before
using the data in their analyses. Ground checks were suspended on 8/3/94.
The algorithms for removing the ground check are:
RH (without ground check) = RH (as reported) - humidity_correction
Temp (without ground chk) = [Temp (as reported) - FACTOR1]/FACTOR2 where
FACTOR1 = [(90*temperature_correction)/(tref+90)
FACOTR2 = [1+(temperature_correction)/(tref+90)
The variables "humidity_correction" and "temperature_correction" are
metadata contained in the netCDF data files from 5/20/93 to 8/3/94.
Between 1/21/93 and 5/20/93 these variables were misnamed and are not
easily accessible via FORTRAN (see PIF 940917.1).
The variable tref is the actual temperature reported by the radiosonde
while in the ground check set. This variable is not included in the
netCDF file and can be estimated by using a value of 15 degC. The
correction function is relatively insensitive to variations in this
value. (see PIF 940917.2)
FORTRAN routines for reading the metadata and for applying the algorithms
to produce "uncorrected" data are available from the instrument mentor.
Other observations/measurements impacted by this problem:
Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)
Send (another) notice to users of the data.
Data Processing Notes Date |
| Measurements: | sgpsondewrpnC1.a1:
sgpsondewrpnC1.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/09/1994 | 1133 | 12/09/1994 | 1133 |
| Subject: | Questionable initial values sounding 941209:1133 |
| DataStreams: | sgpsondewrpnC1.a0, sgpsondewrpnC1.a1 |
| Description: | DQR No: Platform: sgpsondec1
Subject: Questionable initial values sounding 941209:1133
Date Submitted: 12/12/94
Submitted By: Barry Lesht _x_ Instrument Mentor
___ EST Member
___ Science Team Member
___ Other _____________________________
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at dqr@arm.gov.
Platform/Measurement: All
What level data: (raw,a0,a1,b1,c1 etc):
What location was the data collected at: SGP/CF
Period of time in question
Begin Date 12/09/94 Time 11:33:00 (GMT)
End Date 12/09/94 Time 11:33:02 (GMT)
Data should be labeled:
_x_ questionable ___ All data fields affected
___ incorrect _x_ Only some data fields affected
___ wrong calibration
___ others
Discussion of Problem:
It appears that incorrect values were entered for surface temperature and
relative humidity in the subject sounding. The values entered were
temp = 25.1 degC, rh = 18 %. The next values in the sounding are
temp =- 2.4 degC, rh = 70 %. Because these do not appear to be simple
typographical errors, the values should be noted as questionable rather
than incorrect until the paper log can be consulted by site ops.
Initial values for subsequent soundings seem fine.
Other observations/measurements impacted by this problem:
Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)
Check paper log and flag data. Note for possible correction later.
Data Processing Notes Date |
| Measurements: | sgpsondewrpnC1.a1:
sgpsondewrpnC1.a0:
|